I have been running mz’s for years initially ts250 at 50:1 but did have both crank and main bearing failure at different times
For the last 3 years I have run a ts125 I have a wilf green owners handbook that says with the later motors from about 75/76 50:1 is right after being run in at 33:1
I use the cheapest 2t availible (carplan @ 3.50 ish per litre ) at 33:1 and it runs sweet as a nut
Remember 50:1 is 2% oil and 33/1 is 3% thats only 1% less petrol (bugger all difference) use the good petrol the higher octane will outwiegh the less petrol
The measure in the tank is for 1 imperial gallon at 50:1 or 4.5 litres so on that basis 1 measure for 3 litres or 2 for 6 litres or even 3 measures for 9 litres will give you 33:1 🙂 4 scoops to a full tank from reserve will give you somthing like 30:1 and it will still run sweet
Good luck and enjoy your bike